Bellows actuated switch mechanism



April 6, 1965 E. F. PIERCE 3,177,314

BELLOWS ACTUATED SWITCH MECHANISM Filed April 1, 1963 Z4 I 50 A c/WI fierce 5g INVENTOR.

WHANN 8 McMAN/GAL 7 Aflornoys for A i From United States Patent BELLOWS ACTUATED SWITCH MECHANifih i Edwin F. Pierce, Pasadena, Calif., assignor to E. and 1. Engineering Research and Development Corporation, Reno, Nev., a corporation of Nevada Filed Apr. 1, 1963, Ser. No. 269,667

14 Claims. (Cl. 200-453) This invention relates generally to switch mechanisms and particularly relates to. a switch actuated by a bellows to respond to variations of temperature or pressure. I

7 Switches which are actuated by a bellows are well known. For example, many thermostats respond to variations in ambient temperature by contraction or expansion of a bellows to close a switch to turn on, for example, a heating system. Since the movements of the bellows in response to small variations in temperature or pressure are generally very small, it is desirable that this movement be amplified in' an efficient manner. Furthermore, it is usually desirable that the switch mechanism be adjustable so that the exact pressure or temperature at which the switch operates may be controlled.

Frequently, it is desirable to provide a bellows actuated switch mechanism which operates as a limit switch whereby one switch is closed when the pressure or temperature exceeds a certain value while another switch is closed when the temperature or pressure falls below a certain value. p

In addition, it is highly desirable that such a switch mechanism may cheaply be manufactured, that it should be reliable and accurate in operation and have a long life.

The switch mechanism itself of the present invention is of the sliding contact type. In any switch having sliding contacts, the contact pressure is of great importance. When the contact pressure is relatively low, the switch contacts may bounce thus causing erratic signals and increasing the danger of arcing. The arcing in turn will corrode the contacts and thus shorten the life of the switch. On the other hand, when the switch is operated with a relatively high contact pressure, the wear of the contacts increases accordingly. Worn oil metal particles are eventually deposited over the insulating surfaces of the switch so that an electric circuit path is provided even when the switch is in the open position. This is usually referred to as tracking.

It is accordingly an object of the present invention to provide an improved bellows-operated switch which may be maderesponsive to variations in pressure or temperature or which may be designed as a time delay switch.

Another object of the present invention is to provide a bellows-operated switch mechanism having two separate switches which may be arranged as limit switches so that one switch closes when the pressure or temperature exceeds a certain value while the other switch closes when the pressure or temperature falls below a certain value.

A further object of the present invention is to provide a bellows-operated switch mechanism of the type referred to Where the limits of movement of the bellows required to operate each one of the two switches may be separately adjusted at will.

Still another object of the present invention is to provide a switch of the type referred to having contacts of the sliding type provided with an insulating lubricant for embedding metal particles worn off the switch contacts and brushes and for insulating them from each other thereby to minimize tracking.

Still a further object of the present invention is to provide a bellows-operated switch of improved construction which can be cheaply made in mass production, which is accurate and reliable and'has a long useful life.

A bellows-actuated switch mechanism in accordance with the present invention includes a bellows adapted to 3,l?7,314 i ateuted Apr. 6, 1&55

ice

contract or expand in response to variations in pressure or temperature. There is further provided a rotor rotatable in response to contraction or expansion of the bellows. This is preferably accomplished by securing a rack to the bellows which is movable therewith and a pinion in driving engagement with the rack and connected to the rotor so that the pinion is rotatable in response to contraction or expansion of the bellows.

Two conductive contacts are disposed opposite to each other and on the rotor and are preferably flush with the outer surface of the rotor. Means are provided for electrically interconnecting the contacts. Two conductive brushes are further disposed in contact with the outer surface of the rotor. The conductive brushes are engageable with the two contacts upon rotation of the rotor to open or close an electric circuit connected to the brushes. Finally, an insulating lubricant is provided on the contacts and on the brushes for embedding and insulating from each other particles worn oil the contacts and the brushes.

If desired, it is feasible to provide two rotors each secured to the pinion and each having a pair of contacts and a pair of brushes. This makes it possible to open or close two separate electric circuits each being connected to one pair of the brushes.

The novel features that are considered characteristic of this invention are set forth with particularity in the appended claims. The invention itself, however, both as to its organization and method of operation, as well as additional objects and advantages thereof, will best be understood from the following description when read in connection'with the accompanying drawings in which:

FIG. 1 is a longitudinal sectional view of a bellowsactuated switch mechanism embodying the present in vention and responsive to variations in temperature;

FIG. 2 is a longitudinal sectional view taken substantially on line 2-2 of FIG. 1, parts being shown in elevation;

FIG. 3 is a cross sectional view taken substantially on line 3-3 of FIG. 2, parts being shown in elevation; and

FIG. 4 is a broken away longitudinal sectional view, partly in elevation, similar to that of FIG. 1 and illustrating a modified switch mechanism responsive to variations in pressure.

Referring now particularly to FIGS. 1 to 3, there is illustrated a bellows-actuated switch mechanism in accordance with the present invention and responsive to variations in temperature. The mechanism includes essentially a main housing 10, an end plate 11 closing one open end of the housing, a bellows 12 secured to the other open end of the housing 10, a rack and slide 14 secured to the free end of the bellows 12, a pinion 15 meshing with the rack of the rack and slide 14, two contact-carrying rotors 16 and 17 rotatable with the pinion 15, two relatively-fixed brush adjustment rings 20 and 21, each carrying two brushes 22, 2.3 and 24, 25, a brush adjustment pinion 26 and 27 associated individually with each adjustment ring 26 and 21 and a bellows tension spring 28.

The housing It) and at its upper end is provided with an annular recess 30 for receiving a corresponding outer projection 31 of the end plate 11. The end plate 11 is of generally disc shape and is provided with a central cylindrical boss 32 having an internal screw thread 33 into which an adjustment screw 34 may be screwed for increasing or decreasing the tension of coil spring 28. Furthermore, four terminal lugs 35 extend through the end plate 11, two of which are shown in FIG. 1. The terminal lugs 35 are connected to the four brushes 22 through 25 in a manner to be more fully explained hereinafter. Each of the terminal lugs 35 may have a suitable aperture 36 for welding, soldering or otherwise connecting thereto a conductor.

The housing It) at its end opposite the end plate 11 is provided with an annular recess 37 into which extends one end of the bellows 12 which may be provided with a substantially flat end portion 38. The housing is provided with a large inner opening 40 for receiving the rack 14, the pinion 15, the two rotors 16, 17, the brush adjustmentrings 2t), 21 and the brush adjustment pinions 26, 27. Provided centrally in the housing 10 are two bosses 41 each having a central opening 42 for journaling a drive shaft 43 to which the pinion is keyed or otherwise secured.

As shown particularly in FIG. 1 the housing 10 is provided with a semicylindrical recess 44 for receiving therein the lower portions of the two brush adjustment rings and 21. Finally, the housing 10 is provided with a central opening 45 communicating with the interior of the bellows 12 for receiving a rod 46 which in turn is connected with or made integral with the rack 14. The rod 46 may be secured to the closed bottom 47 of the bellows 12, for example, by a screw 48. Thus, it will be evident that expansion or contraction of the bellows 12 due to variation in temperature or pressure will cause a corresponding movement of the rod 46 and of the rack14.

Theslide and rack structure 14 includes a rack 50 and an oppositely disposed slide 51 arranged in such a manner that the teeth of the rack 50 engage with the teeth of the pinion 15 while the pinion teeth bear against the slide 51 to insure that the rod 46 and the rack and slide mechanism 14 is guided to move in a vertical direction in response to contraction or expansion of the bellows without the possibility of lateral movement.

The pinion 15 is secured to the drive shaft 43 which is journaled in the bosses 41 of the housing. The two rotors 16 and 17 are spaced from the pinion 15 by a pair of spacer discs 52 while the two rotors are also keyed or otherwise secured to the drive shaft 43. As a result, the two rotors 16 and 17 rotate in unison with the pinion 15 upon movement of the bellows 12.

As clearly shown in FIG. 1, the rotor 16 is provided with two. conductive contacts 53 and 54. Similarly, the rotor 17 is provided with two contacts, one of which is indicated at 55 and shown in FIG. 2. The two contacts 53 and 54 are electrically interconnected by a conductive rod 56 which extends through the drive shaft 43 as clearly shown in FIG. 1. By way of example, the rod 56 may consist of a pair of telescoping rivets which are electrically connected to the rivet heads or contacts 53 and 54. Preferably, as clearly shown in FIG. 1, the outer surfaces of the two contacts 53 and 54 are flush with the outer cylindrical surface of their associated rotor 16. It will be evident that upon contraction or expansion of the bellows 12 the two contacts 53 and 54 will rotate with respect to their associated brushes 22 and 23 thereby to open or close an electric circuit connected to the two brushes.

The two brushes 22 and 23 are received in suitable pockets 57 which, for example, may be molded in the brush adjustment ring 20. Similarly, the two brushes 24 and 25 are disposed in pockets 58 which may be molded in the other brush adjustment ring 21. Each of the brushes is provided with a bias spring 60 as clearly shown in FIG. 3. The bias springs 60 are preferably coil springs as shown.

Each of the brushes 22, 23, 24, 25 preferably consist of a piece of sheet metal bent to form substantially a U as clearly shown in FIG. 1. Preferably, the contact surface 61 is formed as a substantially rectangular projection. It is also feasible to bend inwardly the free ends of each of the brushes to prevent the occurrence of any sharp corners. Thus, the four brushes 22 through 25 are urged by their bias springs 60 against the surface of the rotors 16 and 17, respectively. It will be noted that each pair of brushes 22, 23 and 24, 25 are disposed diametricallyopposite from each otherwith respect to their associated rotors 16 and 17 so that both brushes 4 contact their associated contacts such as 53 and 54 simultaneously.

Each of the brushes, such as brush 22, is connected by a conductor or jumper contact 62 to one of the terminal lugs 35. The conductors 62 are secured to their brushes and terminal lugs, for example, by welding or soldering.

Preferably, each conductor 62' is connected to its brush in such a manner that the brushes are capable of small movements to remain in contact with their associated rotors 16 and 17. p

It will be noted that the brush adjustment rings 20 and 21 are circumferentially disposed about and spaced from their associated rotors 16 and 17 so that the brushes'contact the outer cylindrical surface of the respective rotors.

16 and 17. Each of the brush adjustment rings 20 and 21 has a laterally extending portion 63 and 64 provided with internal gear teeth 65 as shown clearly in FIG. 1. Preferably, the portions 63. and 64 each form approximately a 909 gear segment which meshes with the teeth of the two respective adjustment pinions 26 and 27. Pinion 26 is keyed to a shaft 66 which in turn is secured to an adjustment knob-67 disposed outside of the housing 19. The shaft 66 extends through the wall of the hous ing. Similarly, the pinion 27 is secured to a shaft 68; extending through the housing wall and secured to another adjustment knob 70.

Accordingly, it will be evident that rotation of the knob 67, for example, will cause a rotation of the brush'adjustment ring 20 which carries the two brushes 22 and 23. This will adjust the relative position between the brushes 22 and 23 and their associated contacts 54 and 53. a This in turn will adjust the amount of travel required of the bellows to open or close a circuit connected to the brushes 22 and 23. 7

Similarly, by adjustment of control knob 70, the brush adjustment ring 21 may be rotated independentlyof ring 211. As a result, the relative position of the brushes 24 and 25 with respect to their contact such as 55 may be adjusted. This separate adjustment of each pair of brushes with respect to their associated two contacts 'makes it possible to provide a limit switch. Such a limit switch will, for example, close an electric circuit when the pressure or temperature exceeds a predetermined value while the other electric circuit connected to the other pair of brushes is closed when the temperature or pressure falls below'a predetermined value;

The bellows tension spring 28' has one end which bears against the adjustment screw 34 while its other end bears against a recess 71 in the rack and slide 14.

Thus by screwing the screw 34 into or out of the housing boss 32, the tension of the spring 28 may be increased or decreased. This in turn increases or decreases the variations in temperature or pressure required to move the bellows 12. In addition, the tension spring 28 tends to dampen out vibrations of the bellows. Of course, the tension spring 28 may be omitted when the spring force of the bellows 12 is sufliciently large.

As shown particularly in FIGS. 1 and 2, the bellows 12 may be surrounded by a heater band 73 having a heater wire 74 embedded therein. This will permit the heating of the bellows 12 at a rate determined by the construction of the heater band 73, by its proximity to the bellows 12 and by the amount of current flowing through the wire 74. In this manner, a time delay switch may be obtained with a variable time delay which can be controlled for example by the current flowing through the wire 74.

Before explaining the operation of the switch-of FIGS. 1 to 3, the materials of which the switch is preferably constructed will now be described.

The housing It) is made of insulating material and preferably of a plastic material which may readily be molded. Thus, for example, the housing 10 may be made of a polycarbonate. A polycarbonateis a polymer derived from biphenol A or 4,4dihydroxy diphenyl propane.

Such a polycarbonate is sold in the trade under the name of Lexan by General Electric Company. This plastic material may readily be molded and can be cheaply made in mass production. It is also characterized by great impact strength.

For ease of assembly, the housing is preferably made of two portions 75 and 76 as clearly shown in FIG. 3. The two housing portions 75 and 76 may be joined together by a suitable cement, by heat sealing or in other expedient manners. Lexan permits also to join the two housing portions by applying a solvent to the surfaces to be joined. The two housing portions may then be put together and are joined when the solvent dries.

Preferably, the rack and slide combination 14 with its rod 46 are made integral and also of Lexan. Lexan may also be used with advantage in molding the drive pinion 15, its shaft 43, the two spacers 52, the two rotors 16, 17, the brush adjustment rings and 21 and the adjustment pinions 26, 27. Similarly, the shaft 66 and 63 of the adjustment pinions with their control knobs 67 and 70 may also be made of Lexan.

The end plate 11 is preferably made of a phenolic resin. A phenolic resin will more readily withstand the relatively high temperatures generated when a conductor is soldered or welded to the terminal lugs 35.

The bellows 12 is preferably made of a beryllium copper alloy or from any other metal or alloy which has good spring characteristics. The tension spring 28 and the various brush bias springs 60 may also be made of berylium copper alloy or some other good spring metal. The conductor 62 may consist of copper as well as the rods or rivets 56. The terminal lugs may, for example, consist of tin-plated brass.

The four brushes 22 through 25 may consist of an alloy known as coin silver which consists of 92% silver and 8% copper. This alloy has a flaking action under wear. However, any other conducting material which has a flaking action may be used for the brushes. Thus, the four brushes may also consist of an alloy known as nickel silver which includes 81% copper and 18% nickel. Alternatively, the brushes may consist of palladium, rhodium, platinum or gold or may be plated therewith. These metals have the property that they are resistant to chemical action and hence the contact surface tends to remain clean. They also have a flaking action which further helps to maintain a clean contact surface. If the various brushes are plated, it is sufiicient to plate the outer surface of the rectangular projection 61 of each brush, which is the only portion of the brush in contact with the respective rotors 16 and 17 and their contacts.

The contacts such as 53 and 54 may, for example, consist of molybdenum. Molybdenum has a surface which has pits or depressions which serve a purpose to be ex plained hereinafter. Additionally, the molybdenum has a high work function. As a result, arcing between the contacts such as 53 and 54 and their cooperating brushes 22 and 23 is minimized. Where arcing is not a problem, the contacts such as 53 and 54 may be made of copper or brass which is nickel plated and which also provides a pitted surface. Instead of nickel plating, the contacts may be plated with or made of tungsten, molybdenum or stainless steel which also provide a pitted surface.

Further in accordance with the present invention, the four contacts such as 53, 54 and 55 and the four brushes 22 through 25 are coated with an insulating lubricant. Preferably, the lubricant has a low surface tension or high wetting action so that the lubricant is retained by the pitted surfaces of the four contacts.

Byway of example, the insulating lubricating material which is used in accordance with the present invention may include a major proportion of mineral oil of the type used for high voltage transformers. This mineral or transformer oil withstands high temperatures as well as low temperatures and has a high dielectric constant because it is used for transformers carrying up to 300,000 volts. This mineral or transformer oil may be emulsified and may have a base of a tallow grease which will not carbonize out under conditions of wear. A mineral detergent may be added to increase the wetting action or decrease the surface tension.

An insulating lubricant of this type is sold in the trade under N0. 871 Switch Lube by Lubrication Company of America. This insulating lubricant includes at least 93% mineral oil and is of relatively high viscosity. Thus, at F, the viscosity may be 2,600 centistokes per second. This mineral oil has a flash point of 550 F. In other Words, when the oil is heated to 550 F., it will flash under the influence of an electric arc. Thus, the lubricant will withstand arcing up to 550 F. It may further be added that No. 871 Switch Lube shows substantially no corrosion.

One of the main purposes of the insulating lubricant is to embed or encapsulate worn off metal particles. During operation of the switch metal particles wear off the contacts such as 54: and 55 and the brushes such as 22 and 23. These metal particles may plate out for example on the insulating outer surface or" the rotor 16 or 17 to cause undesirable short circuits, also called tracking. The lubricating material should have a high dielectric constant so that individual encapsulated metal particles are insulated from each other so they cannot cause short circuits. The contact pressure provided by the bias springs 60 of the various brushes 52 through 55 should be high enough to break through the lubricating film on the contact surfaces.

This construction further makes it possible to operate the switch mechanism of the invention with a high contact pressure which may be desirable for certain applications. In that case, the Wear of the contacts and brushes is increased. Without the provision of such an insulating lubricant, the operating life of the switch would be drastically reduced.

The operation of the switch of FIGS. 1 to 3 providing a time delay switch will now be explained.

Assuming first that the bellows has previously been heated to an elevated temperature by sending electric current through the wire 74. Assuming further that the current through the Wire 74 is reduced so that the temperature developed by the heater band 73 falls. This in turn will cause a contraction of the bellows 12 and a corresponding upward movement of the rod 46 and of the rack 50. Consequently, the drive pinion 15 i rotated in a clockwise direction (as viewed in FIG. 1). At the same time the rotors i6 and 17 will rotate in a clockwise direction as viewed in FIG. 1 so that eventually the contact 54 will contact the brush 22 and the contact $3 will contact the brush 23. At the same time, of course, a circuit connected to the terminal lugs of the two brushes 22 and 23 is closed.

Similarly, the two brushes 24 and 25 are associated with the rotor 17 and will also make contact with their associated contacts depending on the adjustment of the brush adjustment ring 21.

Thus, it is feasible to adjust the two brush adjustment rings 2t? and 21 in the same manner so that all four brushe simultaneously contact their contacts.

As pointed out before, the respective circuits connected to the terminal lugs 35 will close with a time delay which is determined by the properties of the 'heater band 73 and the magnitude of the electric current.

The tension spring 28 may be adjusted by the screw 34 to increase or decrease the temperature variations necessary to move the bellows. At the same time the tension spring 28 tends to dampen vibrations of the bellows.

it is also feasible to utilize the switch mechanism of FIGS. 1 through 3 as a temperature responsive switch which maybe used, for example, as a thermostat. To thi end, all that is necessary is to remove the heater band 73. The bellows 12 is then exposed to vibrations of ambient temperature. When the temperature changes by a predeterminedamount again the rotor 16 and the rotor 17 will be rotated so that eventually the contacts such as 53 and 54 contact thier respective brushes Z3 and 22.

It is.also feasible to arrange the switch mechanism to operate as a limit switch. For example, through the control knob 67 the brush adjustment ring 20 may be set to operate at one desired temperature while the other control knob 70 may be rotated to set the brush adjustment ring 21 to operate at a different temperature. Thus, as. the temperature exceeds a predetermined value, say the circuit connected to brushes 22 and 23v closes. On the other hand, when the temperature falls below a preset value, the circuit through the brushes 24 and 25 may be closed.

The switch mechanism of the present invention may also be used as a pressure-sensitive switch. To this end, the switch mechanism may be modified as illustrated in FIG. 4.v Thus, a threaded sleeve '77 may be secured to or made integral with the housing and surrounds the I bellows 12. Another threaded sleeve '73 engages the threads of the sleeve 77 and is connected to a source of variable pressure which may be greater or less than atmospheric pressure, the pressure variations of which are to be measured. As a result, the outside of the bellows 12 is subjected to pressure variations which in turn cause contraction or expansion of the bellows 12. Otherwise, the operation is the same as previously described and the mechanism may again Ibe adjusted to provide for a limit switch which operates whenever the pressure exceeds or falls below a preset value.

It will also be appreciated that adjustment of each of the brush adjustment rings 20 and 21 may be used to adjust the amount of travel needed by the bellows 12 to open or close its associated contacts.

The rack 50 and the meshing pinion serve the purpose to magnify the motions of the bellows 12. For example, each of the rotors 16 and 17 may have an outer diameter of 0.75 inch with a resulting circumference of 2.356 inches. Thus, for each degree of rotation, the circurrnference of each rotor 16 and 17 and hence of the contact will travel 0.0065 inch. The rack 50 may, for example, be made with an 80 pitch rack. The pinion 15 may be provided with 16 teeth and may have a pitch diameter of 0.2 inch. Accordingly, one inch of rack travel rotates the pinion 1800". In other words, for each 0.001 inch of travel of the rack, the pinion rotates through 1.8". At the same time, the rotor rotates 1.8 times 0.0065 or 0.012 inch. Thus, it will be seen that the magnification of the movement can readily be made twelve times that of the bellows movement.

The assembly of the switch mechanism of the invention will now be described.

At first the brushes such as brushes 22 and 2 3 with their bias springs 60 are inserted into their pockets 57 of the two brush adjustment rings 20. Then the conductors 62 are secured to their brushes and to their associated terminal lugs 35 which are pushed through suitable openings in the end plate 11. Then the various parts are assembled on the drive shaft 43. Thus, the rotor 16, the spacer 52, the pinion 15, the other spacer 52 and the rotor 17 are pushed over the drive shaft 43. Then the rods or rivets 56 are extended through their respective rotors 16 and 17 and connected with their contacts 53 and 54 which may be the rivet heads. Subsequently, the rod 46 is secured to the interior of the bellows 12 by the screw 48. Thereupon, the rack is put over the pinion 15 and the tension spring 28 is put in place in'its recess 71.

The adjustment pinion26 with its shaft 66 and control knob 67 are assembled through one portion of the housing 10. Similarly, the other adjustment pinion 27 with its shaft 68 and control knob 70 are assembled about the other portion of the housing 10. The two adjustment entire switch mechanism is now assembled and is ready for operation after suitable adjustment of the adjustment screw 34 and of the adjustment knobs 67 and 70.

It will be understood that it is also feasible to omit one of the rotors such as rotor 17 with its associated pair of contacts such as 55 and the two brushes 24 and 25. In

that case the brush adjustment ring 21 with its adjustment pinion 27 may also be omitted. Sucha switch will only open or close a single circuit connected to the terminal lugs of the brushes 22 and 23. also feasible to provide more than two pair of brushes such as three or four pairs with associated contacts and associated rotors.

There has thus been disclosed an improved bellowsactuated switch mechanism. The switch mechanism of the invention may respond either to variations in pressure or in temperature. Alternatively, the switch mechanism may be arranged as atime delay switch. The switch mechanism of the invention may be provided with two pairs of brushes and associated contacts in such a manner that the amount of travel of the bellows required to open or close each of the two pairs of contacts may be separately adjusted. Such a switch may be arranged as a limit switch for closing one circuit when the pressure or temperature exceeds a certain value and for closing another circuit when the pressure or temperature falls below a certain value. In addition, an insulating lubricant is provided over the contacts and brushes to embed and insulate from each other metal particles worn off therefrom. This will prevent tracking of the switch and extend its useful life; Furthermore, arcing between the cooperating contacts and brushes is minimized.

The invention and its attendant advantages will be understood from the foregoing description. It will be apparent that various changes may be made in the form, construction and arrangement of the parts of the invention without departing from the spirit and scope thereof or sacrificing its material advantages, the arrangement hereinbefore described being merely by way of example. I do not wish to be restricted to the specific form shown or uses mentioned except as defined in the accompanying claims, wherein various portions have been separated for clarity of reading and not for emphasis.

I claim:

1. A bellows-actuated switch mechanism comprising:

(a) abellows adapted to contract or expand in respons to variations in-pressure or temperature;

(b) a rotor;

(0) means secured to said bellows and movable there-' with for rotating saidrot-or in response to contraction or expansion of said bellows;

(d) a pair of conductive contacts disposed opposite to each other and on said rotor and flush with the outer surface of said rotor;

(6) means electrically interconnecting said contacts;

(7) a pair of conductive brushes disposed in contact with the outer surface of said rotor and engageable with said contacts upon rotation of said rotor to open or close an electric circuit connected tosaid brushes; and

(g) an insulating lubricant provided on said contacts 7 and said brushes for embedding and insulating from each other particles worn off said contacts and brushes. 2. A bellows-actuated switch mechanism comprising: (a) a bellows adapted to contract or expand in response to variations in pressure or temperature;

On the other hand, it is.

([1) a rack secured to said bellows and movable therewith;

(c) a pinion in driving engagement with said rack and rotatable thereby in response to contraction or expansion of said bellows;

(d) a rotor secured to said pinion and rotatable therewith;

(e) a pair of conductive contacts disposed opposite to each other and on said rotor and flush with the outer surface of said rotor;

(1) means electrically interconnecting said contacts;

(g) a pair of conductive brushes disposed in contact with the outer surface of said rotor and engageable with said contacts upon rotation of said rotor t open or close an electric circuit connected to said brushes; and

(h) an insulating lubricant provided on said contacts and said brushes for embedding and insulating from each other particles worn off said contacts and brushes.

3, A bellows-actuated switch mechanism comprising: (a) a bellows adapted to contract or expand in response to variations in pressure or temperature; (/5) a rack secured to said bellows and movable therewith;

(c) a pinion in driving engagement vith said rack and rotatable thereby in response to contraction or expansion of said bellows;

(d) a rotor secured to said pinion and rotatable therewith;

(e) a pair of contacts disposed opposite to each other and on said rotor and flush with the outer surface of said rotor, each contact having a surface layer consisting of a metal having a pitted surface;

(1) means electrically interconnecting said contacts;

(g) a pair of brushes disposed in contact with the outer surface of said rotor and engageable with said contacts upon rotation of said rotor to open or close an electric circuit connected to said brushes, each of said brushes having a surface layer engageable with said contacts consistiru of a metal having a flaking action under wear; and

(h) an insulating lubricant provided on said contacts and said brushes for embedding and insulating from each other metal particles worn off said contacts and brushes, said lubricant having a low surface tension so as to be retained in the pits of said contacts.

4. A bellows-actuated switch mechanism comprising:

(a) a bellows adapted to contract or expand in response to variations in pressure or temperature;

(11) a rack secured to said bellows and movable therewith;

(c) a pinion in driving engagement with said rack and rotatable thereby in response to contraction or expansion of said bellows;

(d) a rotor secured to said pinion and rotatable therewith;

(e) a pair of conductive contacts disposed opposite to each other and on said rotor and flush with the outer surface of said rotor, each of said contacts having a surface layer consisting of a metal having a pitted surface and a high work function to minimize arcs;

(1) means electrically interconnecting said contacts;

(g) a pair of conductive brushes disposed in contact with the outer surface of said rotor and cngageable with said contacts upon rotation of said rotor to open or close an electric circuit connected to said brushes, each of said brushes having a surface layer engageable with said contacts consisting of a metal having a flaking action under wear; and

(h) an insulating lubricant provided on said contacts and said brushes for embedding and insulating from each other metal particles worn off said contacts and brushes, said lubricant having a low surface tension it) so that said lubricant is retained in the pits of said contacts.

5. A bellows-actuated switch mechanism comprising:

(a) a bellows adapted to contract or expand in response to variations in pressure or temperature;

(b)a raclr secured to said bellows and movable therewith;

(c) a pinion in driving engagement with said rack and rotatable thereby in response to contraction or expansion of said bellows;

(d) a rotor secured to said pinion and rotatable therewith;

(e) a pair of metallic contacts disposed opposite to each other and on said rotor and flush with the outer surface of said rotor;

(1) means electrically interconnecting said contacts;

(g) a pair of brushes disposed in contact with the outer surface of said rotor and engageable with said contacts upon rotation of said rotor to open or close an electric circuit connected to said brushes, each of said brushes consisting of a piece of sheet metal of substantially U-shape having a rectangular projection in contact with said outer rotor surface;

([1) spring means for urging each of said brushes against said rotor; and

(i) an insulating lubricant provided on said contacts and said brushes for embedding and insulating from each other metal particles worn off said contacts and said brushes.

6. A bellows-actuated time delay switch mechanism comprising:

(a) a bellows adapted to contract or expand in response to variations in temperature;

(7) a raclc secured to said bellows and movable therewith;

(c) a pinion in driving engagement with said rack and rotatable thereby in response to contraction or expansion of said bellows;

(d) a rotor secured to said pinion and rotatable therewith;

(e) a pair of conductive contacts disposed opposite to each other and on said rotor and flush with the outer surface of said rotor;

(f) means electrically interconnecting said contacts;

(g) a pair of conductive brushes disposed in contact with the outer surface of said rotor and engageable with said contacts upon rotation of said rotor to open or close an electric circuit connected to said brushes;

(h) an insulating lubricant provided on said contacts and said brushes for embedding and insulating from each other particles worn off said contacts and brushes; and

(i) a heater disposed about said bellows for heating said bellows to cause said brushes to contact said contacts with a time delay determined by the rate of the temperature increase of said bellows.

7. A bellows-actuated switch mechanism comprising: (a) a bellows adapted to expand or contract in response to variations in ambient temperature or pressure; (b) a rack secured to said bellows and movable therewith;

(c) a pinion in driving engagement with said rack and rotatable thereby in response to expansion or contraction of said bellows;

(d) a drive shaft secured to said pinion;

(e) a pair of rotors secured to said dn've shaft and rotatable in unison with said pinion;

(f) each of said rotors having a pair of conductive contacts on the circumferential outer surface thereof and flush therewith, each pair of contacts being disposed diametrically opposite with respect to its rotor;

(g) a conductive pin extending through each rotor and said drive shaft for electrically interconnecting each pair of contacts;

(h) a pair of conductive brushes disposed in contact with the circumferential surface of each rotor and relatively fixed with respect thereto, each brush being disposed diametrically opposite to its associated rotor for engagement with the associated pair of contacts to open or close an electric circuit connected to each pair of brushes upon rotation of said rotors; and

(i) an insulating lubricant provided on said contacts and on said brushes for embedding and electrically insulating from each other conductive particles worn off said contacts and said brushes.

8. A bellows-actuated switch mechanism comprising:

(a) a bellows adapted to expand or contract in response to variations in ambient temperature or pressure;

(b) a rack secured to said bellows and movable therewith;

(c) a pinion in driving engagement with said rack and rotatable thereby in response to expansion or contraction of said bellows;

(d) a drive shaft secured to said pinion;

(e) a pair of rotors secured to said drive shaft and rotatable in unison with said pinion;

(1) each of said rotors having a pair of conductive contacts on the circumferential outer surface thereof and flush therewith, each pair of contacts being disposed diametrically opposite with respect to its rotor;

(g) a conductive pin extending through each rotor and said drive shaft for electrically interconnecting each pair of contacts;

(h) a pair of conductive brushes disposed in contact with the circumferential surface of each rotor and relatively fixed with respect thereto, each brush being disposed diametrically opposite to its associated rotor for engagement with the associated pair of contacts to open or close an electric circuit connected to each pair of brushes upon rotation of said rotors;

(i) means for independently adjusting the relative position of each pair of brushes With respect to its associated pair of contacts, thereby to adjust the amount of movement of said bellows required to open or close each of the electric circuits connected to each pair of brushes; and

(j) an insulating lubricant provided on said contacts and on said brushes for embedding and electrically insulating from each other conductive particles worn off said contacts and said brushes.

9. A bellows-actuated, temperature-responsive switch mechanism comprising:

(a) a bellows adapted to expand or contract in response to variations in ambient temperature;

(b) a rack secured to said bellows and movable therewith;

(c) a pinion in driving engagement with said rack and rotatable thereby in response to expansion or contraction of said bellows;

(d) a pair of rotors secured to said pinion and rotatable in unison therewith;

(e) each of said rotors having a pair of conductive contacts on the'circumferential outer surface thereof and flush therewith, each pair of contacts being disposed diametrically opposite with respect to itsrotor;

(f) a conductive pin extending through each rotor for electrically interconnecting each pair of contacts;

(g) a pair of conductive brushes disposed in contact with the circumferential surface of each rotor and relatively fixed with respect thereto, each brush being disposed diametrically opposite to its associated rotor for engagement with the associated pair of contacts to open or close an electric circuit connected to each pair of brushes upon rotation of said rotors;

(h) means for independently adjusting the relative position of each pair of brushes with respect to its associated pair of contacts, thereby to adjust independently the maximum and the minimum ambient temperature required to close one or theother of the two electric circuits connected to each pair of brushes; and

(i) an insulating lubricant provided on said contacts and on said brushes for embedding and electrically insulating from each other conductive particles worn off said contacts and said brushesj 10. A bellows-actuated, pressure-responsive switch mechanism comprising:

(a) a bellows adapted to expand or contract in re sponse to variations in ambient pressure;

(b) a rack secured to said bellows and movable therewith;

(0) means for applying pressure to be sensed to said bellows;

(d) a pinion in driving engagement with said rack and rotatable thereby in response to expansion or contraction of said bellows;

(e) a pair of rotors secured to said pinion and rotatable in unison therewith;

(f) each of said rotors having a pair of conductive contacts on the circumferential outer surface thereof and flush therewith, each pair of contacts being disposed diametrically opposite with respect to its rotor;

(g) a conductive pin extending through each rotor for electrically interconnecting each pair of contacts;

(/1) a pair of conductive brushes disposed in contact with the circumferential surface of each rotor and relatively fixed with respect thereto, each brush being disposed diametrically opposite to its associated rotor for engagement with the associated pair of contacts to open or close an electric circuit connected to each pair of brushes upon rotation of said rotors;

(1') means for independently adjusting the relative position of each pair of brushes with respect to its associated pair of contacts, thereby to adjust independently the maximum and the minimum pressure required to close one or the other of the two electric circuits connected to each pair of brushes; and

(j) an insulating lubricant provided on said contacts and on said brushes for embedding and electrically insulating from each other conductive particles worn off said contacts and said brushes.

11. A bellows-actuated switch mechanism comprising:

(a) a housing;

(b) a bellows adapted to contract or expand in response to variations of ambient temperature or pressure, one end of said bellows being secured to said hous- (c) a rack secured to the other end of said bellows and movable therewith and extending into said housing;

(d) a shaft journaled in said housing;

(e) a drive pinion secured to said shaft and in meshing engagement with said rack to rotate said drive pinion in response to contractions or expansion of said bellows;

(1) two rotors secured to said shaft and rotatable in unison with said drive pinion, each of said rotors having an outer cylindrical surface;

(g) two diametrically opposed conductive contacts disposed on each of said rotors and flush with the outer cylindrical surface thereof;

(h) a rivet extending through each rotor and through said shaft for electrically connecting the two contacts of each rotor;

(i) two brush adjustment rings, each being rotatably mounted in said housing for independent adjustment and being associated with one of said rotors;

(j) two diametrically opposed conductive brushes mounted in each of said rings;

(k) spring means for urging each of said brushes against the cylindrical surface of its associated rotor, whereby each pair of said brushes engages or disen- 13 gages its associated pair of contacts upon rotation of said rotors;

(l) means extending through said housing for rotating each of said adjustment rings independently of the other to adjust the amount of movement of said bellows required to open or close an electric circuit connected individually to each pair of said brushes; and

(m) an insulating lubricant provided on said contacts and said brushes for embedding and insulating from each other conductive particles worn off said brushes and said contacts.

12. A bellows-actuated switch mechanism comprising:

(a) a housing;

(b) a bellows adapted to contract or expand in response to variations of ambient temperature or pressure, one end of said bellows being secured to said housing;

(c) a rack secured to the other end of said bellows and movable therewith and extending into said houss;

(d) a shaft journaled in said housing;

(e) a drive pinion secured to said shaft and in meshing engagement with said rack to rotate said drive pinion in response to contractions or expansion of said bellows;

(1) two rotors secured to said shaft and rotatable in unison with said drive pinion, each of said rotors having an outer cylindrical surface;

(g) two diametrically opposed conductive contacts disposed on each of said rotors and flush with the outer cylindrical surface thereof;

(h) a rivet extending through each rotor and through said shaft for electrically connecting the two contacts of each rotor;

(i) two brush adjustment rings, each being rotatably mounted in said housing for independent adjustment and being associated with one of said rotors;

(i) two diametrically opposed conductive brushes mounted in each of said rings;

(k) spring means for urging each of said brushes against the cylindrical surface of its associated rotor, whereby each pair of said brushes engages or disengages its associated pair of contacts upon rotation of said rotors;

(l) a gear segment secured to each adjustment ring;

(In) an adjustment pinion meshing with each of said gear segments; and

(n) means extending through said housing for rotating each of said adjustment pinions independently of the other to adjust the amount of movement of said bellows required to open or close an electric circuit connected individually to each pair of said brushes.

13. A bellows-actuated switch mechanism comprising:

(a) a housing;

(b) a bellows adapted to contract or expand in response to variations of ambient temperature or pressure, one end of said bellows being secured to said housing;

() a rack secured to the other end of said bellows and movable therewith and extending into said housing;

(d) a shaft journaled in said housing;

(e) a drive pinion secured to said shaft and in meshing engagement with said rack to rotate said drive pinion in response to contractions or expansion of said bellows;

( two rotors secured to said shaft and rotatable in unison with said drive pinion, each of said rotors having an outer cylindrical surface;

(g) two diametrically opposed conductive contacts disposed on each of said rotors and flush with the outer cylindrical surface thereof;

(h) a rivet extending through each rotor and through said shaft for electrically connecting the two contacts of each rotor;

(1') two brush adjustment rings, each being rotatably mounted in said housing for independent adjustment and being associated with one of said rotors;

(i) two diametrically opposed conductive brushes mounted in each of said rings;

(k) spring means for urging each of said brushes against the cylindrical surface of its associated rotor, whereby each pair of said brushes engages or disengages its associated pair of contacts upon rotation of said rotors;

(l) a gear segment secured to each adjustment ring;

(m) an adjustment pinion meshing with each of said gear segments;

(n) means extending through said housing for rotating each of said adjustment pinions independently of the other to adjust the amount of movement of said bellows required to open or close an electric circuit connected individually to each pair of said brushes;

(0) a tension spring disposed between said housing and said rack;

(p) means for adjustably increasing or decreasing the tension of said spring; and

(q) an insulating lubricant provided on said contacts and said brushes for embedding and insulating from each other conductive particles worn off said brushes and said contacts.

14. A bellows-actuated switch mechanism comprising:

(a) a housing;

(b) a bellows adapted to contract or expand in response to variations of ambient temperature or pressure, one end of said bellows being secured to said housing;

(0) a rack secured to the other end of said bellows and movable therewith and extending into: said housing;

(0) a drive shaft journaled in said housing;

(e) a drive pinion secured to said shaft and in meshing engagement with said rack to rotate said drive pinion in response to contractions or expansion of said bellows;

(f) two rotors secured to said shaft and rotatable in unison with said drive pinion, each of said rotors having an outer cylindrical surface;

(g) two diametrically opposed conductive contacts disposed on each of said rotors and flush with the outer cylindrical surface thereof;

(it) a rivet extending through each rotor and through said shaft for electrically connecting the two contacts of each rotor;

(1') two brush adjustment rings, each being rotatably mounted in said housing for independent adjustment and being associated with one of said rotors;

' (j) two diametrically opposed conductive brushes mounted in each of said rings;

(k) a terminal lug electrically connected to each of said brushes and extending through said housing; (1) spring means for urging each of said brushes against the cylindrical surface of its associated rotor,

whereby each pair of said brushes engages or disengages its associated pair of contacts upon rotation of said rotors;

(m) a gear segment secured to each adjustment ring;

(n) an adjustment pinion meshing with each of said gear segments; and

(0) a control knob extending through said housing and secured to each of said adjustment pinions independently for adjustment thereof to control the amount of movement of said bellows required to open or close an electric circuit connected individually to each pair of said terminals.

No references cited.

7 BERNARD A. GILHEANY, Primary Examiner. 

1. A BELLOWS-ACTUATED SWITCH MECHANISM COMPRISING: (A) A BELLOWS ADAPTED TO CONTRACT OR EXPAND IN RESPONSE TO VARIATIONS IN PRESSURE OR TEMPERATUE; (B) A ROTOR; (C) MEANS SECURED TO SAID BELLOWS AND MOVABLE THEREWITH FOR ROTATING SAID ROTOR IN RESPONSE TO CONTRACTION OR EXPANSION OF SAID BELLOWS; (D) A PAIR OF CONDUCTIVE CONTACTS DISPOSED OPPOSITE TO EACH OTHER AND ON SAID ROTOR AND FLUSH WITH THE OUTER SURFACE OF SAID ROTOR; (E) MEANS ELECTRICALLY INTERCONNECTING SAID CONTACTS; (F) A PAIR OF CONDUCTIVE BRUSHES DISPOSED IN CONTACT WITH THE OUTER SURFACE OF SAID ROTOR AND ENGAGEABLE WITH SAID CONTACTS UPON ROTATION OF SAID ROTOR TO OPEN OR CLOSE AN ELECTRIC CIRCUIT CONNECTED TO SAID BRUSHES; AND (G) AN INSULATING LUBRICANT PROVIDED ON SAID CONTACTS AND SAID BRUSHES FOR EMBEDDING AND INSULATING FROM EACH OTHER PARTICLES WORN OFF SAID CONTACTS AND BRUSHES. 